78 Catalina rear end

My rear end snap one day after smashing on the gas so i got one from a salvage yard for cheap. Its out of a 85 buick lesabre. they had two under a 79 bonneville that were 250. i just took the cheap route. wanted to know if it was a bad choice and are there any other b body rear ends that'll fit my catalina

Welcome to the forum! Yes any rear end from 1977-1996 in any b body will fit, it just depends on which one you got. They made the 7.5", 8.5" 10 bolts and the ultra rare 8.75" 12 bolt rear ends. Im assuming since you broke the rear end and if the car is stock, you might have had the 7.5 rear end, those werent very strong, the 8.5 is alot lot stronger. The 8.75 is even bigger and stronger but it was only made for a few years and parts for it are next to impossible to get. Ive only ever seen the 8.75 under impalas, both station wagon and sedan.
Heres a topic on how to id them: https://www.gmbbodyforum.com/t333-how-to-id-your-rear-end-gm-10-12-bolts-7-5-8-5-8-75-8-875#1928

I think you're the first Catalina driver here! Welcome to the forum.

For rear ends, here's what to look for under the 91-96s:

Axle Ratio RPO Code.                   Application
 2.56          GM8                    Std. Roadmaster LT1
 2.73          GU2                     Std. Caprice L99 (exc. 9C1)
 2.93          GW9/GU3            Std. Caprice LT1 (exc. 9C1), Opt. Roadmaster LT1
 3.08          GU4                    Std. Caprice 9C1/LT1 (Police), Std. Impala SS
 3.23          GU5                     Opt. Caprice L99, Std. Caprice 9C1/L99 (Police)
 3.42          GU6                     Std. 91-93 Caprice 9C1/L05, Std. 94+ Fleetwood w/V4P
 3.73          GT4                     Std. 91-92 Fleetwood Brougham w/V4P

*V4P = 7,000 lb. trailer towing package... look for a hitch.

Great information. Thanks for the help

No problem, how did the rear end break? Im curious.

Hi welcome. It don't it take much I snapped 2 Chrysler 8.25s in different cars pretty easily with just a little

enthusiasm on the pedal of healthy 4bbl 318s. I just swapped my 7.5 for a POSI 8.5 from a 94 Buick Roadmaster

and have no regrets at all.

actually got rear ended and it been humming ever since. Then one day i stood up on the gas while turning and it snapped and starting thumping really hard. It has a pontiac 400/TH350

Ow that hurt, sounds like internal damage to an axle from the hit.